The invention relates to waste treatment facilities in general and to means for separating organic wastes from other wastes, means for treating sewage and other liquid with organic wastes therein, and means for collecting methane and other energy producing gases evolved from anaerobic digestion of organic wastes and for maintaining good temperature conditions for anaerobic digestion in particular. Disposal of municipal garbage and the like, and treatment of sewage are major problems confronting society today, resulting in the expenditure of much energy, materials, and effort. According to the present invention, these wastes are disposed of or treated for ultimate disposal with a net generation of energy rather than a consumption thereof. This is accomplished by separation of organic components of municipal garbage, sewage and the like from the non-organic components thereof, and decomposition of the organic portion of the waste in the absence of oxygen (anaerobic digestion) to produce methane. Theoretically, each pound of organic waste digested can be converted to 6 cubic feet of methane, having a BTU content of approximately 6,000.
According to the present invention, production of methane is achieved with a minimum input of energy from exhaustible sources, such as fossil fuels or the like, and with materials that do not offer a significant potential for explosion of the methane gas produced. Radiant solar heat and insulative properties of gas are taken advantage of to produce methane under favorable conditions (approximately 40.degree.-50.degree. C.) without the introduction of accessory heat from exhaustible sources, achievable results ensuing that promise improvement over conventional methane generation system proposals (such as shown in U.S. Pat. Nos. 1,757,262, 1,880,772, and 2,262,576).
According to the present invention, municipal garbage, raw sewage and the like are fed into a loading system, wherein the generally non-decomposable materials are separated from the decomposable organic materials. The non-decomposable materials may be otherwise separated and recycled. Then the organic material-containing liquid is fed into a digestor, and anaerobic decomposition of the organic material takes place. The digestor includes a mixing zone, quiescent zone, and clear zone, and mixing may be provided by suitable "pop-up" rotary mixing means, supplied with clear liquid from the clear zone. Treated liquid substantially free or organic material may be removed from the upper portion of the clear zone, and removed from the digestor. Methane gas and the like evolved by the digestor is collected by a digester cover of flexible material. Acculated gas between the flexible cover and the liquid in the digestor is removed by suitable means for ultimate utilization. The flexible cover may assume an inflated position, wherein heat in the digestor is conserved, a partially deflated position wherein radiant heat absorbed by the cover is transferred to the liquid being treated, and a completely deflated position wherein the liquid is allowed to cool. In this way ideal temperature conditions for anaerobic digestion may be maintained with a minimum energy input, and potential of sparking by frictional movement between components is substantially eliminated.
It is the primary object of the present invention to provide an improved waste treatment facility. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.